The present invention generally relates to a communication network (ATM switching network) with employment of the ATM (Asynchronous Transfer Mode) switching system, and more specifically to such an ATM switching network that in response to a call issued or originated from a subscriber, an ATM switching apparatus sets a plurality of communication channels between this subscriber and other subscribers.
ATM switching networks capable of increasing line utilizing efficiencies and information transfer speeds by switching and transferring the information derived from terminals of subscribers in units of cell have begun to be practically utilized. As to the conventional techniques in this ATM switching network, a B-ISDN (Broadband ISDN) switch network will now be explained in the specification.
In the B-ISDN switching network, a service called as a "multiconnection" is provided which sets a plurality of connections among subscribers. Also, in this switching network, any of these subscribers have the obligation to declare traffic amounts when connections are set. Thus, any of these subscribers who intend to have the multiconnection services individually declare each traffic amount of a plurality of traffic amounts to be set, and then data in the respective connections is transmitted/received within the range of the declared traffic amount.
Further, an ATM switching apparatus of this switching network is equipped with a so-called "usage parameter control" function in order to manage traffics from subscribers. In accordance with this function, the traffic amount is measured in units of connection regardless of whether or not the traffic to be controlled is caused by the multiconnection. In such a case that this measurement result exceeds the declared traffic amount, this traffic is limited.
It should be noted that a detailed description about the ATM switching network of B-ISDN is made in "Pictorial Explanations on B-ISDN" published by OHM Co., Ltd, in 1993, pages 64 to 71.
As previously described, according to the prior art ATM network, the traffic amounts of the respective connections among the plural connections set by the multiconnection service are limited to the traffic amounts declared by the subscriber, so that there is no flexibility in adjustments of these traffic amount among these connections. As a result, in such a case that a traffic happens to occur in a burst mode and therefore such a traffic whose traffic amount exceeds the proposed capacity will occur in a certain connection, a portion of this traffic should be allocated to other connections on the subscriber side. Otherwise, predicting that such a burst mode traffic happens to occur, the subscriber should declare the excessive traffic amount with respect to each of these connections. However, there is such a drawback in the above-explained manner for allocating a portion of the traffic to other connections that the work loads processed by the terminal unit of the subscriber are increased. Furthermore, there is such a limitation that this manner cannot be applied to a certain sort of data. That is, for instance, moving picture/image data which is processed in real time cannot be subdivided into a plurality of connections, and then these subdivided moving picture/image data cannot be transferred. On the other hand, another method for proposing such an excessive traffic amount would allocate the excessive transmission band to the subscriber. Accordingly, the contract fee for the multiconnection service to the subscriber is increased, and at the same time, the utilization efficiency of the ATM network is lowered.
Also, according to the IIU-T (International Telecommunication Union-Telecommunication Sector) recommendation, there is no rule that setting of plural connections in a multiconnection is realized by a single call originating signal. As a consequence, such a subscriber who intends to receive a multiconnection service should transmit the call originating signal with respect to each connection under present conditions.